Dynamic characterization of crystalline and glass phases of deuterated 1,1,2,2 Tetrachloroethane

Abstract

A thorough characterization of the γ, β and glass phases of deuterated 1,1,2,2 Tetrachloroethane (C2D2Cl4) via Nuclear Quadrupole Resonance and Molecular Dynamic Simulations (MDS) is reported. The presence of molecular reorientations was experimentally observed in the glass phase and in the β phase. In the β phase, and from MDS, these reorientations are attributed to two possible movements, i.e. a $180^o$ reorientation around the C2 molecular symmetry axis and a reorientation of the molecule between non-equivalent positions. In the glass phase, the spin-lattice relaxation time T1 is of the order of 16 times lower that T1 in the crystalline phase and varies as $T^{-1}$ below 100 K in good agreement with the strong quadrupolar relaxation observed in amorphous materials and in the glassy state of molecular organic systems. The activation energy of molecular reorientations in the glass phase (19 kJ/mol) is comparable to that observed in the glassy crystal of a "molecular cousin" compound, Freon 112 (C2F2Cl4), for the secondary β-relaxation. Moreover, the on-site orientational motion of Tetrachloroethane molecules offers a new indirect evidence of the prominent role of such orientational disorder in glassy dynamics.

Journal of Chemical Physics (in press)

References in corpus (2)

• $\alpha$- and $\beta$- Relaxation Dynamics of a fragile plastic crystal
• Supercooled-liquid and plastic-crystalline state in succinonitrile-glutaronitrile mixtures

Cited by in corpus (5)

• Glassy anomalies in the low-temperature thermal properties of a minimally disordered crystalline solid
• Thermodynamic and kinetic fragility of Freon113: the most fragile plastic crystal
• Secondary relaxation in the terahertz range in 2-adamantanone from theory and experiments
• Simultaneous Orientational and Conformational Molecular Dynamics in Solid (1,1,2)-Trichloroethane
• Dynamic heterogeneity in an orientational glass